What is nystagmus?

Nystagmus: Definition, Types, and Clinical Implications

Nystagmus is defined as rhythmic, involuntary eye movements that typically consist of a slow pathological drift followed by a fast compensatory movement (refixation saccade) back to the primary position. 1

Types of Nystagmus

Based on Time of Onset:

• Infantile Nystagmus: Appears within the first 3-6 months of life 2

  • Can be idiopathic or associated with:
    • Albinism 3
    • Retinal diseases 3
    • Low vision 3
    • Visual deprivation (e.g., congenital cataracts) 3
    • Fusion maldevelopment syndrome 3

• Acquired Nystagmus: Appears later in life 2

  • Associated with:
    • Anterior optic pathway lesions 3
    • Brainstem/cerebellum lesions 3
    • Metabolic diseases 3
    • Multiple sclerosis 3
    • Vestibular disorders 3

Based on Direction and Pattern:

• Horizontal Nystagmus: Most common form 4

  • Geotropic type: Fast component beats toward the ground 5
  • Apogeotropic type: Fast component beats away from the ground 5

• Vertical Nystagmus: 4

  • Downbeat nystagmus: Strongly suggests disorders affecting the cerebellum or cervicomedullary junction 3, 6
  • Upbeat nystagmus: Associated with midbrain or medulla lesions 1

• Torsional Nystagmus: Rotational eye movements 4

• Mixed Patterns: Combinations of horizontal, vertical, and torsional movements 4

Clinical Manifestations

• Cardinal symptoms: 1

  • Blurred vision
  • Jumping images (oscillopsia)
  • Reduced visual acuity
  • Sometimes double vision

• Associated symptoms (depending on etiology): 1

  • Permanent dizziness and postural imbalance (typical of downbeat and upbeat nystagmus)
  • Spinning vertigo with tendency to fall (in acute cases)
  • Positional vertigo

Diagnostic Approach

• Clinical examination: 4

  • Assess eye position, spontaneous nystagmus, range of eye movements
  • Evaluate smooth pursuit, saccades, gaze-holding function
  • Test vestibulo-ocular reflex (VOR) and visual fixation suppression

• Specific tests: 5

  • Supine roll test: Identifies lateral semicircular canal BPPV
  • Dix-Hallpike maneuver: Helps differentiate central from peripheral causes

• Neuroimaging: 3, 6

  • MRI of the brain is preferred for evaluating nystagmus, particularly for:
    • Acquired nystagmus
    • Late onset nystagmus
    • Concurrent neurological symptoms
    • Asymmetric/unilateral/progressive nystagmus

Differential Diagnosis

• Otologic disorders: 5, 6

  • Ménière's disease
  • Vestibular neuritis
  • Labyrinthitis
  • Superior canal dehiscence syndrome

• Neurologic disorders: 5, 6

  • Vestibular migraine
  • Posterior circulation stroke
  • Demyelinating diseases
  • Central nervous system lesions

• Other entities: 5

  • Anxiety or panic disorder
  • Cervicogenic vertigo
  • Medication side effects
  • Postural hypotension

Clinical Pearls and Pitfalls

• Central vs. Peripheral Nystagmus: 7

  • Central nystagmus (e.g., gaze-evoked) typically does not fatigue and is not easily suppressed by visual fixation
  • Peripheral nystagmus usually has a torsional component and is suppressed by visual fixation

• Red Flags: 3, 6

  • Asymmetrical or unilateral nystagmus suggests neurological disease
  • Downbeat nystagmus without a torsional component suggests central cause
  • Direction-changing nystagmus and baseline nystagmus indicate central pathology

• Special Considerations in Children: 2, 8

  • Spasmus nutans: Rare form characterized by nystagmus, head bobbing, and torticollis
  • Unilateral nystagmus in children can indicate anterior visual pathway lesion
  • Seesaw nystagmus may be associated with suprasellar and mesodiencephalic lesions

Management Approaches

• Pharmacological options: 4, 8

  • 4-aminopyridine for downbeat and upbeat nystagmus
  • Memantine or gabapentin for pendular fixation nystagmus
  • Baclofen for periodic alternating nystagmus
  • Carbonic anhydrase inhibitors may help some forms

• Surgical interventions: 8

  • Eye muscle surgery (Anderson or Kestenbaum procedure) to correct nystagmus-related anomalous head posture
  • Four-muscle-tenotomy has limited positive effect on visual acuity

• Optical management: 8

  • Correction of even minor refractive errors
  • Contact lenses may offer advantages over glasses